package leetCode.sum;

public class ListNode {
    int val;
   ListNode next;
    ListNode() {}
    ListNode(int val) { this.val = val; }
    ListNode(int val, ListNode next) { this.val = val; this.next = next; }

    public ListNode(int[] arr){
        if (arr == null || arr.length == 0 ){
            throw new IllegalArgumentException("arr is imPty");
        }

        this.val = arr[0];
        ListNode cur = this;
        for (int i = 1; i < arr.length; i++) {
            cur.next = new ListNode(arr[i]);
            cur = cur.next;

        }

    }

    @Override
    public String toString(){
        StringBuilder builder  = new StringBuilder();
        ListNode cur = this;
        while (cur!=null){
            builder.append(cur.val + "->");
            cur  = cur.next;
        }
        builder.append("null");
        return builder.toString();
    }
}
